Reserve one meter of space between residences. Respect a neighbor’s right to build up, obstructing your view. If adding a window would compromise privacy, build a wall instead.

These are the rules of mutual respect that govern favela design and construction, enforced by tight-knit, multi-generational communities. Even the “barn raising”-style process of building a new home or a new floor reinforces the unofficial norms, as friends come together on weekends to barter for materials and help one another complete construction.

“The favela follows its own rules, its own logic, and its own codes,” Solène Veysseyre writes in ArchDaily’s case study of Complexo do Alemão, a favela in Rio de Janeiro.

The result is a stark landscape borne of necessity, with hidden worlds of color and hospitality within. Function determines the form of home exteriors, with brick walls and star-like security bars on windows. Materials have to be cheap and durable, as well as light and small enough for men to carry through the narrow streets.